Field of the Invention
The present disclosure relates to a light emitting device, and more specifically to a side-view type light emitting device that can emit light in a direction substantially parallel to an upper surface of a mounting substrate for mounting the light emitting device.
Description of Related Art
Light emitting devices using a light emitting element, such as a light emitting diode, are easily reduced in size and can have high light emission efficiency.
As one of the light emitting devices using the light emitting element, a side-view type light emitting device is known that can emit light in the direction substantially parallel to an upper surface of a mounting substrate. For example, as disclosed in JP 2008-198807 A, the conventional side-view type light emitting device includes a resin package with a cavity serving as a side surface side opening in a mounted state, and two leads with exposed parts located at the bottom (back) of the cavity and the side surface of the resin package (particularly, side surface serving as a mounting surface). A light emitting element (semiconductor chip) is mounted on one of the two leads. One of p-side and n-side electrodes of the light emitting element is electrically connected to one lead by a metal wire, while the other of the p-side and n-side electrodes of the light emitting element is electrically connected to the other lead by a metal wire.
When mounting the light emitting device with this structure on the mounting substrate, the two leads exposed at the mounting surface are electrically connected to a wiring layer on the mounting substrate by soldering or the like.
In this way, power can be supplied to the light emitting element, so that light emitted from the light emitting element in the cavity goes directly straight or is reflected by a wall surface of the cavity to pass through an opening on the side surface of the resin package in the direction substantially parallel to the upper surface of the mounting substrate. Asa result, a sufficient amount of light can be emitted in the direction substantially parallel to the upper surface of the mounting substrate.
Thus, the side-view type light emitting device serves as a compact light source for backlighting that can supply the sufficient amount of light by placing the cavity facing an end surface of a light guide plate of a small or medium-sized liquid crystal display, for example, used in a cellular phone (including a smartphone), a lap-top computer, a tablet and the like. That is, the use of the side-view type light emitting device can provide a compact and/or light-weight liquid crystal display that exhibits high brightness with a little power consumption.
In this way, the thus-obtained side-view type light emitting device can ensure the sufficient brightness with low power consumption, while achieving the reduction in size and/or weight of the device itself. Thus, the side-view type light emitting device can be used in a variety of applications, including various types of meters (or indicators), a read sensor, an illumination lamp and the like, in addition to the liquid crystal display.
Various devices using a side-view type light emitting device, such as a display, are increasingly required to be reduced in size and/or weight.
In particular, the reduction in size (thinning) of the light emitting device in the thickness direction (direction perpendicular to the mounting surface) is profoundly desired, for example, in a display, as it directly leads to thinning of the display. Further, in any application other than the display of various meters, read sensor, and illumination lamp mentioned above, the entire light emitting device can also be thinned, for example, by reducing the thickness of a light guide plate. For this reason, the thinning of the side-view type light emitting device is strongly required.
In the conventional structure, however, as mentioned above, the light emitting element is disposed at the exposed part of the lead positioned at the bottom of the cavity provided in the resin package. For this reason, a certain level of the thickness of the resin package, specifically, an interval between the surface of the resin package and the cavity surface needs to be set adequate for the device. Further, in order to insert the light emitting element into the cavity or the like, some gap (interval) also needs to be ensured between the light emitting element and a wall surface of the cavity (that is, an inner surface of the resin package).
Therefore, there was limitation on thinning of the conventional side-view type light emitting devices.